After clicking Branding, under the Settings menu, you will see a Branding Guide orange button in the top right. Click this and you will be prompted to type in a URL.
After typing in your organizations URL, click the orange Fetch Information button. We will scrape the website and pick up logos, colors, footers, and background images (results may vary). Click the Save Theme so you can edit or update it later. You can now upload your logo to your account.